Although the prevalence of family-friendly policies in US workplaces has increased dramatically in recent years, few have been studied using scientifically sound designs. To address this critical gap, the NIH and the CDC formed the Work, Family, and Health Network (WFHN). During Phase 1, WFHN designed and conducted multiple pilot and feasibility studies. For Phase 2, the WFHN has been called upon to implement an innovative intervention based on Phase I pilot studies and to evaluate the intervention using a group randomized experimental design. The goal of the proposed study is to assess the effects of a workplace intervention designed to reduce work-family conflict, and thereby improve the health and well being of employees, their families, and their workplaces. The study intervention is grounded in theory from multiple disciplines and supported by findings from our pilot/feasibility studies on the importance of increasing family supportive supervisor behaviors and employees' control over work. We will assess the efficacy of the intervention via group-randomized field experiments, one at each of two employers representing different industries. Within each industry partner, 30 worksites of 50-120 employees each will be randomly assigned to intervention or usual practice conditions. All employee and supervisor participants will be assessed at baseline and at 6-, 12-, and 18-months post baseline, including survey interviews and health assessments of cardiovascular risk and sleep dysregulation based on selected biomarkers and actigraphy. Employees' spouse/partners and/or children (one resident child per employee) aged 10-17 years will be assessed to document the impact of the intervention on family functioning. In addition, to provide a more detailed perspective on the temporal relationship of work-family conflict and health, a sub-sample of 500 employee participants and their child will participate in a daily diary assessment including telephone interviews and saliva sampling. Our process evaluation documents details of intervention fidelity, implementation, and dose received by participants. The WFHN will also translate findings to business environments and other public media channels. The study holds great promise for informing the implementation of evidence-based family friendly policies, and therefore improving the health and well-being of employees and their families nationwide. The Portland State University, Center for Work-Family Stress, Safety, and Health, was established during Phase 1 of the WFHN, and is applying to serve as one of 4 Research Units (RU) for Phase 2. Our center has experience in designing, implementing and evaluating worksite interventions within the retail/service industry, and expertise in occupational health psychology, organizational behavior, human resource and employer work-family policy implementation, contributing significantly to the Phase 2 WFHN. We have primary responsibility for developing and maintaining the relationship with one of the employers.